[clang] [llvm] [RISCV] Implement the implications of C extension (PR #132259)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-x86_64-debian-dylib` running on `gribozavr4` while building `clang,llvm` at step 8 "test-build-unified-tree-check-lld".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/60/builds/22785

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 8 (test-build-unified-tree-check-lld) failure: test (failure)
******************** TEST 'lld :: ELF/lto/riscv-attributes.ll' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 3: rm -rf /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/lto/Output/riscv-attributes.ll.tmp && split-file /b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/lto/riscv-attributes.ll /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/lto/Output/riscv-attributes.ll.tmp && cd /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/lto/Output/riscv-attributes.ll.tmp
+ rm -rf /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/lto/Output/riscv-attributes.ll.tmp
+ split-file /b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/lto/riscv-attributes.ll /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/lto/Output/riscv-attributes.ll.tmp
+ cd /b/1/llvm-x86_64-debian-dylib/build/tools/lld/test/ELF/lto/Output/riscv-attributes.ll.tmp
RUN: at line 4: /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-mc -filetype=obj -triple=riscv32 1.s -o 1.o
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-mc -filetype=obj -triple=riscv32 1.s -o 1.o
RUN: at line 5: /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-mc -filetype=obj -triple=riscv32 2.s -o 2.o
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-mc -filetype=obj -triple=riscv32 2.s -o 2.o
RUN: at line 6: /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-as a.ll -o a.bc
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-as a.ll -o a.bc
RUN: at line 7: /b/1/llvm-x86_64-debian-dylib/build/bin/ld.lld 1.o 2.o a.bc -o out
+ /b/1/llvm-x86_64-debian-dylib/build/bin/ld.lld 1.o 2.o a.bc -o out
RUN: at line 8: /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-readelf --arch-specific out | /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/lto/riscv-attributes.ll
+ /b/1/llvm-x86_64-debian-dylib/build/bin/llvm-readelf --arch-specific out
+ /b/1/llvm-x86_64-debian-dylib/build/bin/FileCheck /b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/lto/riscv-attributes.ll
/b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/lto/riscv-attributes.ll:13:15: error: CHECK-NEXT: expected string not found in input
; CHECK-NEXT: SectionLength: 98
              ^
<stdin>:3:13: note: scanning from here
 Section 1 {
            ^
<stdin>:4:2: note: possible intended match here
 SectionLength: 119
 ^

Input file: <stdin>
Check file: /b/1/llvm-x86_64-debian-dylib/llvm-project/lld/test/ELF/lto/riscv-attributes.ll

-dump-input=help explains the following input dump.

Input was:
<<<<<<
           1: BuildAttributes { 
           2:  FormatVersion: 0x41 
           3:  Section 1 { 
next:13'0                 X error: no match found
           4:  SectionLength: 119 
next:13'0     ~~~~~~~~~~~~~~~~~~~~
next:13'1      ?                   possible intended match
           5:  Vendor: riscv 
next:13'0     ~~~~~~~~~~~~~~~
           6:  Tag: Tag_File (0x1) 
next:13'0     ~~~~~~~~~~~~~~~~~~~~~
           7:  Size: 109 
next:13'0     ~~~~~~~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/132259